The disclosure of the following priority application is herein incorporated by reference in its entirety: Japanese Patent Application No. 2000-078022 filed Mar. 21, 2000.
1. Field of Invention
The invention relates to a drive apparatus, an exposure apparatus, and to a manufacturing method using the same. In particular, the invention relates to a drive apparatus that drives an object within a two dimensional plane including a first axis and a second axis orthogonal to the first axis, and to an exposure apparatus in which the drive apparatus serves as a mask drive apparatus, and to device manufacturing methods using the same.
2. Description of Related Art
In a lithography process for manufacturing semiconductor devices, liquid crystal display elements, and the like, stationary type exposure apparatus such as the conventional step-and-repeat reduction projection exposure apparatus (a so-called xe2x80x9cstepperxe2x80x9d) have been used. In recent years, along with the advent of highly integrated semiconductor devices and the increased size of wafer substrates and masks or reticles (hereinafter called a xe2x80x9creticlexe2x80x9d), scanning exposure apparatus such as stepand-scan type exposure apparatus (a so-called xe2x80x9cscanning stepperxe2x80x9d), which successively transfers a reticle pattern to a substrate via a projection optical system while moving a reticle and a substrate along a predetermined scanning direction in a synchronous manner are becoming mainstream. These scanning exposure apparatus are capable of exposure of a larger field while using a smaller projection optical system compared to a stepper. As a result, there are advantages in that the manufacture of the projection optical system is less complicated, a high throughput can be achieved, along with an averaging effect due to relative scanning of the substrate and the reticle for a projection optical system, and improved focus depth and distortion.
However, a scanning exposure apparatus requires a drive apparatus for driving a reticle on the reticle side (of the projection optical system) in addition to a stage apparatus on the substrate side for driving a substrate. Scanning exposure apparatus in recent years have used a macromotion and micromotion mechanism in a reticle stage apparatus having a reticle macromotion stage that is moved in a predetermined stroke range in the scanning direction by a pair of linear motors placed on both sides of the stage relative to the non-scanning direction, which is orthogonal to the scanning direction, and that is float supported by air bearings, and the like on a reticle platform. This macromotion stage serves as a drive apparatus on the reticle side. In addition, a reticle micromotion stage is provided, which is slightly driven by voice coil motors, and the like in the scanning direction, the non-scanning direction and the yawing direction.
However, with the conventional drive apparatus on the reticle side mentioned above, the stage apparatus necessarily becomes large due to the linear motors being disposed on both sides of the reticle macromotion stage for driving the reticle macromotion stage in the scanning direction. Also, with this drive apparatus, it is necessary to exchange the reticle (i.e., when a reticle having a different pattern is needed) from a predetermined side relative to the scanning direction (i.e., the side without a laser interferometer for measuring the scan direction position of the reticle micromotion stage (and reticle macromotion stage)), or to move the reticle loader from one side relative to the non-scanning direction, straddle the linear motor stationary member, move onto the reticle stage, and change the reticle.
In the case of the former, it is difficult to obtain a degree of freedom of placement for a reticle loader and a laser interferometer, and, in the case of the latter, up and down movement equal to or greater than the predetermined stroke of at least the reticle loader or the reticle is necessary, and the reticle change sequence necessarily becomes complicated.
Also, because a pair of linear motors for driving in the scanning direction is necessary, the entire drive apparatus becomes larger and heavier.
The application of a drive apparatus capable of moving a stage in a predetermined long stroke direction (i.e., the scanning direction) with an object placed on it, and capable of micromotion in the rotation direction and the direction orthogonal to the long stroke direction is not limited to exposure apparatus, but may also be applied as a sample positioning apparatus in other high precision machines, and the like. It is preferable that such positioning apparatus also be small and light weight.
The invention was conceived in consideration of such problems, and one object of the invention is to provide a small, yet light weight drive apparatus capable of driving an object in a predetermined direction and capable of micromotion in the rotation direction and in the direction orthogonal to the predetermined direction.
Another object of the invention is to provide an exposure apparatus capable of high precision exposure, and capable of obtaining a degree of freedom of placement for each member that is provided in the vicinity of the mask.
A further object of the invention is to provide a highly integrated device having a detailed pattern with excellent precision, and a manufacturing method of the same.
One aspect of the invention relates to a drive apparatus for driving an object within a two-dimensional plane including a first axis and a second axis orthogonal to the first axis. The drive apparatus includes a first stage on which the object is placed. In addition, a micromotion mechanism slightly drives the first stage in the second axis direction and in the rotation direction about a third axis that is orthogonal to the two-dimensional plane. A second stage holds the first stage in a non-contact manner. A non-contact holding mechanism disposed between the first stage and the second stage holds the first stage to the second stage in a non-contact manner which allows for micromotion of the first stage in the second axis direction and in the rotation direction relative to the second stage. A macromotion mechanism drives the second stage in the first axis direction. The second stage, the non-contact holding mechanism, the micromotion mechanism, and the macromotion mechanism are all placed on one side of the first stage, displaced from the third axis.
Accordingly, a non-contact holding device is disposed between the first stage on which an object is placed and the second stage, and the first stage is held to the second stage in a non-contact manner allowing micromotion of the first stage in the second axis direction and in the rotation direction relative to the second stage. Also, the macromotion mechanism drives the second stage with the first stage in the first axis direction. In addition, the micromotion mechanism slightly drives the first stage in the rotation direction (yawing direction) about the third axis orthogonal to the two-dimensional plane and in the second axis direction. Accordingly, it is possible to adjust the position of an object placed on the first stage with excellent precision in the direction of the second axis and in the yawing direction.
Also, the second stage, the non-contact holding mechanism, the micromotion mechanism, and the macromotion mechanism are all arranged on one side of the first stage on which the object is placed. In other words, the first stage is so-called cantilever supported by the second stage, non-contact holding mechanism, micromotion mechanism, macromotion mechanism, and the like. Therefore, on the other side of the first stage there is no drive system, and thus sufficient space is obtainable. It is sufficient to equip the drive apparatus with at least one macromotion mechanism, a linear motor and the like for stage driving for example, on one side of the first stage.
Therefore, it is possible to drive an object in a predetermined direction (first axis direction), slightly in the rotation direction and in a direction orthogonal to the predetermined direction (the second axis direction), and to make the apparatus smaller and lighter in weight.
According to another aspect of the invention, the non-contact holding mechanisms include electromagnets disposed on the first stage or on the second stage, and magnetic material disposed on the other one of the first stage and the second stage. The non-contact holding mechanisms slightly drive the first stage relative to the second stage in the first axis direction by adjusting the magnetic strength generated by the electromagnets. In such a case, it is not only possible to adjust the position of an object placed on the first stage with excellent precision in the second axis direction and in the yawing direction by the micromotion mechanism, but it is also possible to slightly adjust the object position in the direction of the first axis by the non-contact holding mechanism.
According to another aspect of the invention, the non-contact holding mechanism may also generate a slight drive force in the first axis direction at the center of gravity of the first stage. In such a case, it is possible to prevent unnecessary yawing when making micro adjustments to the first stage position in the first axis direction by the non-contact holding mechanism.
According to another aspect of the invention, the micromotion mechanism includes a plurality of moving members disposed on the first stage, a plurality of voice coil motors comprising stationary members corresponding to each of the moving members, and generating a drive force in the second axis direction by electromagnetic interaction between each moving member. The drive force in the second axis direction within the two-dimensional plane preferably includes the center of gravity of the first stage. In such a case, it is possible to prevent the generation of unnecessary rolling and pitching when slightly driving in the second axis direction of the first stage and in the rotation direction (yawing direction) by the micromotion mechanism. In this case, it is preferable that the micromotion mechanism generate a slight drive force in the second axis direction at the center of gravity position of the first stage when slightly driving the first stage in the second axis direction.
According to another aspect of the invention, the macromotion mechanism is a linear motor including moving members disposed on the second stage, and stationary members to generate a drive force in the first axis direction by electromagnetic interaction with the moving members. In addition, the micromotion mechanism includes a plurality of moving members disposed on the first stage, and a plurality of voice coil motors comprised of stationary members corresponding to each of the moving members and generating a drive force in the second axis direction by electromagnetic interaction with each moving member. A frame is provided on which is disposed the linear motor moving members, each stationary member of the plurality of voice coil motors, a first guide surface to support the second stage in a non-contact manner in the second axis direction, and a second guide surface to support the first and second stages in a non-contact manner in the third axis direction. In such a case, since linear motor moving members form the macromotion mechanism, each stationary member of a plurality voice coil motors forms the micromotion mechanism, a guide surface to support the second stage in a non-contact manner in the second axis direction, and a guide surface to support the first and second stages in a non-contact manner in the third axis direction are disposed on a frame, it is possible to drive the second stage with the first stage as one body in the first axis direction relative to the frame in a non-contact manner by the macromotion mechanism, and to slightly drive the first stage in the second axis direction and the yawing direction relative to the frame in a non-contact manner by the micromotion mechanism during movement.
According to another aspect of the invention, a supporting mechanism is provided to support the frame in a non-contact manner such that the frame is free to move as a result of the reaction force to the drive force of the first and second stages. In such a case, when the first stage is driven in the second axis direction, the moving members of a plurality of voice coil motors comprising the micromotion mechanism are driven with the first stage as one body, and the reaction force to the drive force acts on the frame on which the stationary members of the voice coil motors are disposed. However, since the frame is supported in a non-contact manner by a supporting mechanism such that free movement of the frame is possible, the frame absorbs the reaction force according to the law of conservation of momentum by moving a small distance based on the reaction force. Thus, the center of gravity of the system including the second stage and the frame is maintained in a predetermined position. Also, when the second stage is driven with the first stage in the first axis direction, the moving members of the linear motors comprising the macromotion mechanism are driven with the second stage as one body, and the reaction force to that drive force acts on the frame on which the stationary members of the linear motors are disposed. However, since the frame is supported in a non-contact manner by a supporting mechanism such that free movement of the frame is possible, the frame absorbs the reaction force according to the law of conservation of momentum, and the center of gravity of the system including the first and second stages and the frame is maintained in the predetermined position. Therefore, when the first stage and the second stage are driven, it is possible to cancel with certainty the reaction force to the drive force for each stage, and it is possible to prevent the generation of an unbalanced load that would occur if there was movement of the center of gravity.
According to another aspect of the invention, a vacuum preload hydrostatic gas bearing may be disposed on the opposing surfaces of each guide surface of each stage, and have a compressed gas exhaust nozzle and an exhaust groove linked to a vacuum exhaust duct formed around the exhaust nozzle disposed on the bearing surface of each hydrostatic gas bearing. In such a case, is possible to support each stage with high rigidity by maintaining a fixed gap between the guide surfaces by a balance between the static compressed gas jetted from an exhaust nozzle on the bearing surface of the vacuum preload hydrostatic gas bearing disposed opposing each guide surface and the vacuum exhaust force (vacuum suction force) via the exhaust groove and the vacuum exhaust duct. Also, it is possible to prevent leakage of compressed gas for floatation to the vicinity of the bearing.
According to another aspect of the invention, the first stage may be held in a cantilever manner relative to the third axis direction by at least one of the frame and the second stage. In such a case, it is possible to make the apparatus lighter in weight as well as use the space obtained by such a structure for another purpose.
Another aspect of the invention relates to an exposure apparatus for transferring a mask pattern onto a substrate by concurrent movement of a mask and a substrate, and includes a drive apparatus as described above, wherein a mask serves as the object placed on the first stage; and a substrate stage which moves synchronously in the first axis direction with the first stage.
Accordingly, since a mask serving as an object is placed on the first stage having the drive apparatus, it is possible to place the complete drive system including the second stage, the non-contact holding mechanism, the micromotion mechanism and the macromotion mechanism, and the like, on one side of the first stage, and to obtain sufficient space on the other side of the first stage. By this arrangement, it is possible to obtain a degree of freedom for the placement of each member of the apparatus located in the vicinity of the mask, and since up and down movement of the mask loader, and the like is nearly unnecessary when changing the mask, it is possible to simplify the change sequence as well.
Also, as mentioned above, it is possible to make the drive apparatus smaller and lighter, particularly the moving members (especially of the second stage) that are driven during movement in the first axis direction of the first stage on which a mask is placed. Because of this, high precision exposure is possible by means of improved ability to synchronously control movement between the first stage, on which a mask is placed, in the first axis direction and the substrate stage holding a substrate, and improved throughput is possible by means of shortened concurrent settling time.
Another aspect of the invention is a device manufacturing method including a lithographic process that performs exposure using an exposure apparatus as set forth above. Accordingly, since exposure is performed in the lithographic process using an exposure apparatus as set forth above, it is possible to improve the productivity (including yield) of highly integrated micro devices.
Another aspect of the invention relates to the resulting device made by the above-described exposure apparatus.